The present invention relates generally to using an electrochromic window as part of the display screen of a portable device, in particular a mobile telephone. The aim of the invention is improve the design flexibility of the display and to minimize the power consumption of the portable device.
Users of portable devices such as mobile telephones continually require more and more functions. This means that the display sections of these devices need to show more and more information. Often, this can lead to more confusion rather than understanding. In addition, because there is more information being displayed, the power consumption of the device increases. The present invention aims to overcome these disadvantages by using an electrochromic window to enhance the portable device""s conventional display.
Electrochromism is a term used to describe the phenomenon that certain materials can change colour (i.e. change their optical absorption) reversibly when their composition is changed by use of an electrochemical cell. An electrochromic window is therefore a device that can switch colour dynamically by applying a voltage. The degree of coloration can be controlled by the amount of charge passed through the cell. Electrochromic windows typically require low power and are stable in any given state, i.e. they keep the same colour after being switched off.
Electrochromic windows are typically thin film devices that can be coated onto glass. A typical application is for tinting the windows on cars or buildings to prevent sunlight from passing through.
According to a first aspect of the invention, there is provided a portable device having a display comprising first and second elements, wherein the first element is adapted to display information, and the second element is an electrochromic element, which at least partially covers the first element.
This has the advantage of allowing the electrochromic window to enhance the design flexibility of the display.
Preferably, the first element is the standard display of a mobile telephone, or other portable device such as a personal organizer or laptop computer.
According to a second aspect of the invention, there is provided a method of saving power in a portable device having a display comprising first and second elements, the first element being adapted to display information and the second element being an electrochromic element, which at least partially covers the first element, the method comprising the steps of:
a) switching off the first display element when the device is placed into a standby mode; and
b) switching the electrochromic element into a non-transparent state.
This has the advantage of saving power since the first element is turned off, and instead, the low power electrochromic window is used to indicate that the device is in the standby mode.